| Quantity | Symbol, equation | Value |
|---|
| standard gravitational accel. | g | 9.806 65 m s-2 |
| speed of light in vacuum | c | 299 792 458 m s-1 |
| Planck constant | h | 6.626 068 96 x10-34 J s |
| Planck constant, reduced | ℏ = h/2π | 1.054 571 628 x10-34 J s = 6.582 118 99 x 10-22 MeV s |
| electron charge magnitude | e | 1.602 176 487 x10-19 C = 4.803 204 27 x 10--10 esu |
| conversion constant | ℏc | 197.326 9631 MeV fm |
| conversion constant | ℏ2 | 0.389 379 304 GeV2 mbarn |
| electron mass | me | 0.510 998 910 MeV/c2 = 9.109 382 15 x 10-31 kg |
| proton mass | mp | 938.272 013 MeV/c2 = 1.672 621 637 x 10-27 kg
= 1.007 276 466 77 u = 1836.152 672 47me |
| unified atomic mass unit (u) | (mass 12C atom)/12 = (1 g)/(NA mol) | 931.494 028 MeV/c2
= 1.660 538 782 x 10-27 kg |
| permittivity of free space | ε0 = 1/μ0c2 | 8.854 187 817 x 10-12 F m- |
| permeability of free space | μ0 = 4π x 10-7 N A-2 | 12.566 370 614 x 10-7 N A-2 |
| fine-structure constant | α = e2/4πε0ℏc | 7.297 352 5376 x 10-3 = 1/137.035 999 |
| classical electron radius | re = e2/4πε0 mec2 | 2.817 940 2894 x 10-15 m |
| (e- Compton wavelength)/2π | λ = ℏ/mec = reα-1 | 3.861 592 6459 x 10-13 m |
| Bohr radius | (mmnucleus = ∞) a∞ = 4πε0ℏ2/mee2 = reα-2 | 0.529 177 208 59 x 10 -10 m |
| Rydberg energy | hcR∞ = mee4/2(4πε0)2 ℏ2 = mec2α2/2 | 13.605 691 93 eV |
| Thomson cross section | σT = 8πre2/3 | 0.665 245 8558 barn |
| Bohr magneton | μB = eℏ/2me | 5.788 381 7555 x 10-11 MeV T-1 |
| nuclear magneton | μN = eℏ/2mp | 3.152 451 2326 x 10-14 MeV T-1 |
| Avogadro constant | NA | 6.022 141 79 x 1023mol-1 |
| Boltzmann constant | k | 1.380 6504 x10-23 J K-1
= 8.617 343x10-5 eV K-1 |
| molar volume, ideal gas at STP | NAk(273.15 K)/(101 325 Pa) | 22.413 996 x 10-3 m3 mol-1 |
| Wien displacement law constant | b = λmaxT | 2.897 7685x10-3 m K |
| Stefan-Boltzmann constant | σ = π2k4/60ℏ3c2 | 5.670 400 x 10-8 W m-2 K-4 |